1. Field of Invention
The invention relates to optical discs used to store digital information and corresponding optical discs drives used to reproduce data from such discs.
2. Description of Prior Art
The optical disc and corresponding disc reading apparatus of the present invention are a divergence from other forms of laser read optical media including optical discs such as the Video Disc, the Compact Disc (CD-ROM) with associated drive and the Digital Video Disc (DVD-ROM) with its associated drive. A brief description of these will be set forth in the following paragraphs.
Compact discs (CDs) or Compact Disc-Read Only Memory (CD-ROM) are currently available with a capacity of 640 M bytes. The CD-ROM drive reads data in binary format from a number of pits and stripes arranged on the reflective surface of the compact disc (CD). If the laser signal strikes a stripe on the CD surface and is reflected back toward the source it is routed to a receptor head and interpreted as the number 1. If the signal is not reflected back (due to the presence of a pit on the surface of the disc) and is not routed to the receptor head, the output is a 0. In this manner, data is encoded onto the disc in binary format. (See FIGS. 1 and 2)
Digital Video Discs (DVDs) have an increased capacity over CDs, storing up to 4.7 G bytes of data per disc. The drive still reads in binary, as with its CD predecessor, however, the DVD achieves the much larger capacity by placing the data pits on the disc surface closer together and by arranging them such that two different wavelengths of laser light read two separate layers of data. DVDs function much the same as CDs in that the laser light is directed at the surface of the disc and if reflected back toward the source a 1 is interpreted and if not reflected a 0 is interpreted, thus storing and retrieving data in binary format. (Similar to the CD illustrated in FIGS. 1 and 2)
Subsequent to the drives described previously, optical discs have been designed which store digital information in a plurality of pits within a single informational unit, instead of a single pit (or the absence thereof) in each informational unit on the disc. By creating varied patterns of pits, the light reflected back from the disc creates patterns of light intensity that are interpreted to reproduce the data from the disc. Diffraction gratings have also been used to reflect incident light to a number of receptors.
The present invention differs from prior art in that it uses raised pads to store information rather than pits (whether singular in each informational unit or plural) or diffraction gratings which allows the present invention to reflect light to an exponentially larger number of receptors. It also diverges from previous inventions in its use of a receptor ring that surrounds and is attached to the laser light source and moves with the said source in order to maintain constant distance and angle between the light source, the informational unit being read from the disc surface and the receptors in the ring.
And lastly, the present invention differs from previous inventions in that the receptors in the ring are dynamically interpreted by a processor and can be combined to form logical receptors as noted in claim 8 of the present invention.
Other optical discs have been patented which store digital information in a plurality of pits within a single informational unit, instead of a single pit (or the absence thereof) in each informational unit on the discs. By creating varied patterns of pits, the light reflected back from the disc creates patterns of light intensity that are interpreted to reproduce the data from the disc.
Others have used diffraction gratings to reflect incident light to a number of receptors. The present invention differs from prior art in that it uses raised pads to store information rather than pits (whether singular in each informational unit of plural) or diffraction gratings. It also diverges from previous inventions in its use of a receptor ring that surrounds and is attached to the laser light source and moves with the said source in order to maintain constant distance and angle between the light source, the informational unit being read from the disc surface and the receptors in the ring. And lastly, the present invention differs from previous inventions in that the receptors in the ring are dynamically interpreted by a processor and can be combined to form logical receptors as noted in claim 3 of the present invention.
The object of the present invention is to set forth an optical disc device (and associated optical disc) that is capable of reading data that is stored in higher level number systems (Octal, Hexadecimal. etc. up to 1 kbit or higher) in order to store data very densely on the disc by utilizing a raised pad, rather than a pit or pattern of pits, in each of the informational units on the disc. These raised pacts reflect light in a straight line at one of 1024 angles so as to strike one (or a logical grouping) of the 1024 receptors in a receptor ring that is arranged circumferentially around and attached to the laser source. The receptor ring moves with tile laser light source as it moves in its path radially along the disc surface and maintains constant distances between the light source, the disc surface (and informational units thereon) and the receptor ring.
The second object of the present invention is to provide an apparatus for reproducing information from the disc noted in the first object, by sequentially irradiating the raised pads in the information units on the disc with laser light and by detecting the light reflected back from these raised pads to a ring of receptors that is arranged circumferentially around the laser light source and attached to the same source so that it moves with the light source as the disc is read. When a receptor in this ring is irradiated by light reflected from the disc, a signal is sent to a processor which outputs an integer that corresponds to the individual receptor that generated the signal. Therefore the angle of reflection of each pad on the disc corresponds to a particular receptor in the ring, which when irradiated generates a signal that causes the processor to output an integer corresponding to the receptor. Thus, due to the angle of each pad, each informational unit stores an integer that can be read and output sequentially by the apparatus.
It is the third object of the present invention to provide an apparatus according to the second object which combines groups of adjacent receptors to form logical receptors in order to increase the size of the receptor to decrease the complexity (and associated production expenses and intricacies) but which also decreases the overall capacity of the disc. This is done by the processor (noted in the preceding paragraph), which determines the order in which receptors are irradiated with light. When combining physical receptors into logical receptors, the processor accepts signals from any receptor in a logical group as being from a single receptor and outputs an integer associated with the group rather than the integer associated with tile individual receptor. Thus a number of physical receptors are combined to form a single logical receptor dynamically.